ain_4
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ain_4 [2016/08/10 18:41] – [BOM V1.2] latigid_on | ain_4 [2016/08/13 17:35] – [Schematic] latigid_on | ||
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For bipolar operation, a +5V reference may be switched in. The output of the first stage is interrupted by a pot in order to attenuate the signal. The second stage has variable gain from -1 to -0.5 by way of a switched resistor. Hence one can easily select between 0-5V, 0-10V and +/- 5V input ranges to optimise the signal amplitude reaching the ADC. Because the second op amp is powered at the same voltage as the MCU (ideally the same rail), its inputs are protected from over- and under-voltages. | For bipolar operation, a +5V reference may be switched in. The output of the first stage is interrupted by a pot in order to attenuate the signal. The second stage has variable gain from -1 to -0.5 by way of a switched resistor. Hence one can easily select between 0-5V, 0-10V and +/- 5V input ranges to optimise the signal amplitude reaching the ADC. Because the second op amp is powered at the same voltage as the MCU (ideally the same rail), its inputs are protected from over- and under-voltages. | ||
+ | |||
+ | Note the gain calculation, | ||
---- | ---- | ||
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^Type | ^Type | ||
^resistors^ | ^resistors^ | ||
- | | | + | | |
- | | | + | | |
^capacitors^ | ^capacitors^ | ||
- | | |4|10p|025X050|C1, | + | | |4|10p|025X050|C1, |
| |9|100n|025X050|C10, | | |9|100n|025X050|C10, | ||
| |3|10u|electrolytic 2,5-6|C9, C11, C19|remove 1 if powering from Core| | | |3|10u|electrolytic 2,5-6|C9, C11, C19|remove 1 if powering from Core| | ||
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* four 10p as marked in pink | * four 10p as marked in pink | ||
* electrolytics in yellow | * electrolytics in yellow | ||
- | * blue are optional | + | * blue are optional |
* remainder are 100n. | * remainder are 100n. | ||
{{: | {{: | ||
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* with a 100k pot facing you, solder the left leg to 0V(ground) | * with a 100k pot facing you, solder the left leg to 0V(ground) | ||
+ | * with the pot turned anticlockwise, | ||
* centre to WIPER | * centre to WIPER | ||
* right to LEG | * right to LEG |
ain_4.txt · Last modified: 2016/08/18 09:36 by latigid_on